I've done quite a few free software projects and hacks over the years; none of them really big:

sirc, a perl IRC client

xtris, a multi-player tetris for X11

I worked on EFnet's ircd quite a lot a few years back

I took over development of YTalk, since no-one else was doing it, and it needed a lot of fixing to work properly under Linux.

Nowadays I don't have as much time to do free software as a hobby (I got a job, I'm no longer a student), but now I'm working on a component-based templating system for Apache+mod_perl, which will get released under the GPL, in a few weeks.